1. Field
One or more embodiments relate to a solid proton conductor for a fuel cell, and a fuel cell using the same.
2. Description of the Related Art
The development of a hydrogen conductive material that conducts protons at high temperatures and under low humidified conditions, is one of the issues that is to be improved in polymer electrolyte membrane fuel cell (PEMFC) technology.
An electrolyte membrane that may be operated at high temperatures may be obtained by replacing water used in an existing acid electrolyte membrane or by using a hydrogen solvent having a high boiling point. Accordingly, an electrolyte membrane including phosphoric acid and polybenzimidazole and which may be operated in a fuel cell at temperatures of up to 200° C. has been reported.
However, a catalyst in the fuel cell may be poisoned by the phosphoric acid, or the phosphoric acid may be washed away by a reactant while operating a PEMFC for a long time at temperatures of 100° C. or lower.
As a proton conductor that may replace water at a temperature of about 150 to about 250° C., a heterocyclic compound, such as imidazole, pyrazole, or benzimidazole, has been developed (Journal of The Electrochemical Society, 2007, 154(4) 290-294).
The heterocyclic compound has autoprotolysis, and forms a hydrogen bond network, and thus is known to have higher hydrogen conductivity than water.
However, the heterocyclic compound is volatile since a molecular weight of the heterocyclic compound is low. Accordingly, in order to apply the heterocyclic compound in a fuel cell to be operated at high temperatures, the heterocyclic compound is to be directly fixed to a polymer electrolyte membrane in order to maintain liquidity and hydrogen ion mobility, and many synthesizing processes are to be performed. Moreover, a yield of the heterocyclic compound is low.